Protective helmets of the aforedescribed type are known for a variety of uses and in many configurations, sizes, and structural organizations.
For example, they may be used by motorcyclists and even bicyclists, by others engaged in racing sports and, indeed wherever there is a danger that the user may be thrown from his perch on a vehicle or other traveling object, and wherever the speed of travel or the environment is such as to require the use of a visored helmet.
In summary, the basic elements of such a helmet are the impact-resistant shell which can be composed, at least in part, of an impact-resistant synthetic resin or plastic material, possibly reinforced, e.g. with fiberglass or other filaments, generally of a uniform thickness and shaped to enclose substantially all of the head above the chin of the user. This shell can be provided with a window which can be covered by a movable or immovable visor which is transparent to allow the user to see through the window and yet be protected from the elements.
The bottom of the window is generally delimited by the chinpiece previously described, which can be a separate element, or is formed unitarily with the shell, and practically all of the inwardly turned surfaces of the shell can be lined with a padding designed to absorb shocks and generally formed from a foamed synthetic resin material. Edges of the shell may be further cushioned by more dense padding materials or linings so as to eliminate exposed sharp edges.
It has long been recognized that it is desirable to provide ventilation for such helmets. Typical of the publications, patents and other literature describing such helmets are the references listed below:
U.S. Pat. Nos. 3,925,821; 3,788,935; 3,763,494; 3,661,662; 3,914,494; 3,783,450; 3,711,864; 3,491,055; 1,456,824; 3,906,546; 3,769,144; 3,700,535; 3,344,433; 3,825,469; 4,081,865; 3,245,087; 3,116,488; 3,466,219; 3,444,288; 3,116,490; 3,496,854. PA0 English Pat. No. 1,456,824, German patents or patent publications No. 20 50 297, No. 23 44 821, No. 26 39 185, No. 74 084, No. 566,178, and No. 688,965.
The conventional helmets of this type have openings at various places on the shell or other means through which fresh air for ventilating the space between the head and the shell and the space between the face and the visor can enter. They also may have openings through which the ventilating air may leave and, in some cases, are provided with shutters or the like for the controlling airflow. Specifically, the air may be caused to pass between the padding above and around the scalp, i.e. above and around the parietal, temporal and occipital regions of the head, and the shell, e.g. through passages defined between the padding and the shell.
It has been found, however, that with such prior art systems insufficient airflow is directed over the visor and especially over the surface of the visor immediately juxtaposed with the nose and mouth of the user to prevent clouding or fogging of the visor by the breath of the user. As a consequence, the visor may become obscured and result in danger to the user.
Furthermore, the region of the chinpiece generally encompasses a portion of the neck of the user and experience has shown that this region is insufficiently ventilated or cooled so that the skin can be overheated in the region of the neck or throat utilizing conventional helmets designed to enclose the entire head.